- only affects systemd-networkd-using builds (MINIMAL images?)
- does NOT affect NetworkManager
- this allows network administrators to give out IPv6 addresses over DHCPv6 based on the MAC address (which should be stable) instead of systemd's own notion of it's "DUID", which is based on the machine-id and changes on every redeployment
- Rename extensions with "net-*" prefix
- Put the extensions into their own folder
- Split off time sync packages into their own extensions to be able to be used separately
- Put their config files into directories instead of using inline `cat <<- EOF >`
- Move some other NetworkManager related stuff into the extension
- Remove unneeded steps
- Install iproute2 by default on all images (for the `ip` command)
